The objective of the BAlloon Expandable vs. Self-Expanding Transcatheter VaLve for Degenerated Bioprosthesis (BASELINE) trial is to compare the balloon-expandable SAPIEN/MYVAL transcatheter heart valve (THV) series with the self-expanding EVOLUT THV series in symptomatic patients with a failing surgical aortic bioprosthesis. The study is based on the premise that the supra-annular self-expanding EVOLUT THV is superior to the balloon-expandable SAPIEN/MYVAL THV series with respect to the primary endpoint of device success at 30 days.
To date, 360 of the planned 440 patients have been enrolled. During a steering committee meeting in November 2025, it was decided to extend patient enrollment beyond the original study population. With this communication, we aim to inform the cardiovascular community and the readership of American Heart Journal about the details and rationale for study extension as well as the modifications made to the previously published study protocol. , The updated patient flow chart is presented in Figure.
Patient flow chart. Once the enrolment target for any valve arm is reached, enrolment for that arm will be closed and no further patients will be recruited (target for Myval 150, Sapien 150 and Evolut 300).
The revised protocol defines a total study population of 600 patients, divided into two cohorts:
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A primary cohort ( n = 440) consisting of patients with a failing surgical aortic bioprosthesis (aortic stenosis with or without aortic regurgitation) and selected for transfemoral TAVI by heart-team consensus; and
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A continued enrolment cohort ( n = 160) comprising patients enrolled after completion of the primary cohort.
The primary study results will be reported upon completion of the primary cohort ( n = 440) in accordance with the original protocol. , The continued enrolment cohort is designed to address a secondary objective: comparison of the safety and efficacy of balloon-expandable SAPIEN versus MYVAL THV series in the treatment of failing surgical aortic bioprostheses. To ensure balanced representation of balloon-expandable platforms, the total sample size allows inclusion of 150 patients treated with SAPIEN and 150 with MYVAL, in addition to 300 with the self-expanding EVOLUT THV. The continued enrolment cohort is powered to test the hypothesis that the MYVAL THV series is associated with a lower incidence of clinically significant (moderate or severe) prosthesis–patient mismatch compared with the SAPIEN THV series (15% vs. 29%) With 150 patients per group, this difference can be detected with 80% power at a two-sided alpha of 0.05, accounting for potential dropouts.
